Telescopic crane jib

ABSTRACT

A telescopic crane jib of the kind comprising individual telescopic parts which have means by which they are locked together when they are telescopically extended is provided with a mechanism for extending and retracting the parts and this mechanism is capable of operation with the jib in a vertical position so that it is not subjected to any bending moments owing to its own weight during extension. This enables an overlap between the telescopic parts to be avoided and the locking means are arranged to lock the parts together end to end. A jib housing surrounds the telescopic parts when they are in their retracted positions and this housing is at least twice as long as each of the telescopic parts. The housing has at its upper end a releasable catch device which is operative to hold a telescopic part in position above the housing after it has been extended from within the housing and this extension is preferably effected by a single-acting hydraulic cylinder which is fixed to the lowest telescopic part and has a piston extending downwards from it and acting on the bottom of the housing.

United States Patent [1 1 Eucken [451 Feb.4, 1975 1 1 TELESCOPIC CRANE .118

Harry Eucken, Hochdahl-Millrath, Germany [73] Assignee: Leo Gottwald, K.G.,

Dusseldorf-Holthausen, Germany [22] Filed: Oct. 29,1973

[21] Appl. No.: 410,400

[75] Inventor:

[56] References Cited UNITED STATES PATENTS 990,570 4/1911 Lavery 52/115 2,708,493 5/1955 Badertscher et a1 52/111 X 2,819,803 1/1958 Obenchain 212/55 2,961,837 11/1960 Suderow 52/115 X 3,101,816 8/1963 Fox 52/118 3,346,281 10/1967 Thompson 52/115 3,361,456 1/1968 Durrand 52/111 X 3,398,492 8/1968 Nansel 52/115 3,631,988 l/1972 Noly 212/55 X 3,670,465 6/1972 Cheze 52/115 X 3,688,455 9/1972 Zebuhr 52/114 X FOREIGN PATENTS OR APPLICATIONS 723,535 6/1942 Germany 52/111 1,206,213 12/1965 Germany 212/55 1,328,991 4/1963 France 212/46 A 191,949 2/1964 Sweden 52/111 255,261 1/1913 Germany... 52/111 1,217,041 5/1966 Germany 212/55 Primary ExaminerErnest R, Purser Assistant Examiner-Leslie A. Braun Attorney, Agent, or Firm-Toren and McGeady [57] ABSTRACT A telescopic crane jib of the kind comprising individual telescopic parts which have means by which they are locked together when they are telescopically extended is provided with a mechanism for extending and retracting the parts and this mechanism is capable of operation with the jib in a vertical position so that it is not subjected to any bending moments owing to its own weight during extension. This enables an overlap between the telescopic parts to be avoided and the locking means are arranged to lock the parts together end to end. A jib housing surrounds the telescopic parts when they are in their retracted positions and this housing is at least twice as long as each of the telescopic parts. The housing has at its upper end a releasable catch device which is operative to hold a telescopic part in position above the housing after it has been extended from within the housing and this extension is preferably effected by a single-acting hydraulic cylinder which is fixed to the lowest telescopic part and has a piston extending downwards from it and acting on the bottom of the housing.

24 Claims, 20 Drawing Figures PATENTEDFEB I 3.863.407

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PATENIEU FEB 41975 SHEET 17 8F 17 1 TELESCOPIC CRANE JIB This is a Continuation-in-Part of application Ser. No. 225,566 filed Feb. ll, i972, now abandoned.

This invention relates to telescopic crane jibs the individual telescopic parts of which are positively locked together, for example by bolts. after the jib has been extended.

Existing telescopic crane jibs have the considerable disadvantage that the full length of each telescopic part cannot be utilised in extending the jib because the jib is being extended it is usually either horizontal or nearly so. With the jib in this position the comparatively heavy. telescopic parts overlap or interfit for a substantial length to enable them to withstand the bending moments induced in them owing to their horizontal attitude until they have been locked together. Even so the bending stresses due to the weight of the jib may alone be sufficient to damage the telescopic parts where they come into contact with each other at the overlap before locking.

The object of the present invention is to provide a telescopic crane jib in which substantially the full lengths of the individual telescopic parts are utilised. The jib may also be lighter in weight and easier to set up and extend than conventional telescopic jibs.

To this end according to this invention, a telescopic crane jib comprises individual telescopic parts which have locking means by which they are positively locked together when they are telescopically extended and means capable of extending and retracting the parts with the longitudinal axis of the jib at least substantially vertical, the locking means being situated at the ends of the telescopic parts and being arranged to lock the parts together end to end.

When the jib is at least substantially vertical, the individual telescopic parts are in stable, balanced positions and consequently bending moments do not occur to any great extent. Under these circumstances the individual telescopic parts can be extended to their full lengths end to end. A further advantage obtained is that no additional structural parts are necessary for guiding the telescopic parts during the extension of the jib. Consequently it is possible to use telescopic parts of kinds which are unsuitable for use in conventional telescopic jibs because they are difficult to guide and, in conventional jibs, require the use of additional guiding parts. In particular various lattice frame constructions can now be used.

According to a preferred feature of the invention, there is a jib housing which surrounds the telescopic parts when they are in their retracted positions, the housing being at least twice as long as each telescopic part and having at its upper end releasable catch means for holding a telescopic part in position after it has been extended from within the housing by the extending and retracting means.

This arrangement makes it possible to utilise the weight ofthe telescopic part for facilitating the retracting operation. When the jib is being extended all the telescopic parts are lifted together until the releasable catch means engages with the telescopic part which is the next to be extended. whereupon the other telescopic parts, nested together, are allowed to move downwards again. The telescopic part which is retained by the catch means remains suspended from the top of the housing so that this telescopic part is extracted from within the other parts. The other telescopic parts continue to move downwards, under gravity until they reach their lowermost positions in the housing.

The extending and retracting means preferably comprises a single-acting fluid pressure-operated cylinder fixed to the lowest telescopic part and having a piston extending downwards from it. This enables it to lift all the telescopic parts simultaneously. The telescopic parts are nested together, the one within the other, so that they support each other.

The upward thrust which the cylinder has to apply in lifting the telescopic parts can be reduced by using telescopic parts of lattice frame construction. Furthermore the work which the cylinder has to do can be reduced by attaching a head-stay cable to the head of the jib. The head-stay cable reduces the bending load on the jib when the jib is supporting a working load. This allows the telescopic parts of the jib to be of lighter and less costly construction.

The extension of the telescopic parts to their full lengths is facilitated in accordance with a further feature of the invention, by making the internal cross section of the upper end of each telescopic part smaller than the external cross section of the lower end of the telescopic part within it. During the extension of the jib this prevents the extended telescopic parts from becoming detached from the remaining telescopic parts, which are still nested together. The arrangement also simplifies the control of the fluid pressure-operated cylinder. To provide the telescopic parts with the required cross section sizes at their upper and lower ends, each telescopic part may have, at its upper end, one or more inwardly directed limit stops to limit the telescopic extension of the part within it. When the jib is being extended the limit stop or stops locate the telescopic parts accurately in position relative to each other, irrespective of slight inaccuracies in the applied movements. Preferably, there are a number of oppositely situated pairs of limit stops. This prevents the telescopic parts from assuming tilted attitudes relative to each other.

Each telescopic part is preferably of square or other rectangular cross section, the cross section being decreased at the top and increased at the lower end.

Preferably, the locking means are arranged to operate in two stages, the locking means transmitting compressive forces after operation of the first stage and tensile forces as well after operation of the second stage.

Each locking device may comprise two bolts and a support, the two bolts being positioned in line with each other and being slidable in directions perpendicular to the longitudinal axis of the jib, the two bolts slid ing in opposite directions in two adjacent telescopic parts in such a way that when the one bolt has been advanced the two bolts are accurately aligned with each other by the support and advancement of the other bolt causes the two bolts to engage with each other.

The support may be fixed to one of the adjacent telescopic parts, or can form a part of the telescopic part itself, if desired projecting from it. The support preferably has an opening which corresponds to the crosssection of the bolt of the adjacent telescopic part and is in line, in the direction of the longitudinal axis of the jib, with this bolt, so that when this bolt has been advanced into its locking position and the telescopic part moves downwards relative to the support, the bolt comes to rest on the support.

The bolt which cooperates with the support may have an opening in which the other bolt engages when it is advanced in the direction of the first bolt in the second stage of the locking operation.

The opening in the first bolt may for example be a central bore and the other bolt has a projection on its end facing the first bolt, the projection being arranged to engage in the bore when the centres of the two bolts are equidistant from the support. The two bolts of the locking device are preferably actuated by fluid pressure-operated cylinders. The bolts may be provided with auxiliary safety devices which can for example be manually actuated. Means may be provided for delivering a warning signal if the safety devices are not engaged. Operation of the safety devices causes the signal to cease.

Locking devices mounted at the ends of the individual telescopic parts are preferably also capable of locking the telescopic parts to the housing when they are nested within the housing. The telescopic parts may then be locked at both their upper and lower ends. For this purpose the locking bolts may engage in sleeves or openings in the telescopic parts and in the jib housing, the sleeves or openings having wedge surfaces for compensating for manufacturing tolerances in the distances between the locking means at the upper and lower ends of the telescopic parts.

The lock may be made safe by a wedging device which may comprise thrust pins which move perpendicular to the longitudinal axes of the bolts, each thrust pin being thrust against its bolt by fluid pressureoperated cylinders acting through a wedge.

When the telescopic parts are nested together they may be locked to each other at both ends by means of locking bolts which have wedge surfaces or the like cooperating with corresponding wedge surfaces in the openings. This arrangement has the advantage that a firm connection without free play is obtained even if the distances between the locking devices vary by a few millimetres due to manufacturing tolerances The locking bolts preferably lie on the diagonals of the jib cross section. This is to ensure that no torsional moments about the longitudinal axis of the jib can be transmitted to the fluid pressureoperated cylinder or other extending and retracting means.

The releasable catch means fixed to the jib housing may comprise a number of spring loaded catches or gravity loaded catches, arranged so that they can be released, either by hand or by means of fluid pressureoperated cylinders or by means of levers. When the catches are released the telescopic parts are lowered by gravity.

A jib in accordance with the invention may also include a telescopic part which forms a telescopic peak jib. Such a jib can be constructed as described above. The peak jib can be the innermost telescopic part of a main jib, being extended from and retracted into the jib housing with the other telescopic parts. On the other hand ifdesired the peak jib can be in the form ofa telescopic part which opens apart in halves when the jib is extended.

Two examples of crane jibs in accordance with the invention are illustrated in the accompanying drawings, in which:

FIG. I is a diagrammatic longitudinal section through a first example showing the parts telescoped together;

FIG. 2 is a cross section taken along the line II--II in FIG. 1;

FIG. 3 is a cross section taken along the line IIIIII in FIG. 1;

FIGSv 4, 4a, 4b, 5, 6 and 7 show the crane jib shown in FIG. 1 in several different stages of extension;

FIG. 8 shows a device for locking together the tele scopic parts of the crane jib shown in FIG. 1;

FIG. 8a is a cross section taken along the line VIIIaVIIIa in FIG. 8;

FIG. 8b is a cross section taken along the line VIIIb-Vlllb in FIG. 8;

FIG. 8c is a view similar to FIG. 8 illustrating a warning arrangement for the locking device;

FIG. 8d is a schematic showing of the control system for the warning arrangement shown in FIG. 8c;

FIG. 9 is a section taken along the line lX-IX in FIG. 8;

FIGS. 10, II and lla show further examples of locking devices for locking together the telescopic parts of the crane jib shown in FIG. 1;

FIG. 12 shows the crane jib shown in FIGS. 1 to Ila incorporated as part of a mobile crane, the remainder of which is shown only diagrammatically; and

FIG. 13 shows a second example.

The telescopic crane jib shown in FIG. I has a jib housing 1 and three telescopic parts 2, 3, 4. As shown in FIGS. 2 and 3 each telescopic part in square in cross section corresponding to the square cross section of the jib housing 1. Both the housing and the telescopic parts are of lattice frame construction with tubular frame members.

In addition to the telescopic parts 2, 3 and 4 the crane jib also has short peak outriggers 5 and 6. FIGS. 1, 4, 4a and 4b are longitudinal sections taken along a diagonal of the housing and telescopic sections. When the crane jib is being telescopically extended or retracted the movements of the telescopic parts, that is to say the parts 2, 3. 4 and the peak outriggers 5, 6, are all moved by a single hydraulic cylinder 8, which is single-acting. The bottom of the cylinder 8 is fixed rigidly to the lowest telescopic part2. A piston rod 7 of the hydraulic cylinder has its lower end fixed to the bottom of the jib housing 1. The lowest telescopic part 2 is guided in its telescoping movements by rollers 9 which roll along rails I0 of the jib housing 1. When the lowest telescopic part 2 is moving upwards in the jib housing 1 it carries upwards with it the other two telescopic parts 3 and 4 and the peak outriggers 5, 6, because bases 11, 12, I3 of these parts are supported on a base I4 of the lowest telescopic part 2.

The three telescopic parts 2, 3 and 4 are all of the same length. This length is less than half the length of the jib housing I. When the crane jib has a vertical attitude, as shown in FIG. 1, the jib is extended telescopically by repeated strokes of the cylinder 8, that is to say it is extended in several stages, each extension movement being terminated by a locking together of the individual telescopic parts 2, 3. 4 and of the peak outriggers 5 and 6.

the telescopic extension of the jib is effected as follows: First of all the jib is brought to a vertical attitude, as shown in FIG. I, by means of a head-stay cable 25 and a retraction mechanism acting on the cable. The jib is locked in the vertical attitude by a telescopic rod device 26. When this has been done the cable can be slackened. In the next stage of the operation. starting 

1. In a telescopic crane jib including an axially elongated jib housing, a plurality of axially elongated individual telescopic parts selectively displaceable between a fully retracted position with all of said parts within said housing and a number of extended positions and during the extending and retracting operations said jib housing and telescopic parts are arranged approximately vertically, and means for positively locking said telescopic parts together in the extended positions, wherein the improvement comprises that each said telescopic part comprises a base at its lower end extending transversely of its elongated direction, a rim at its upper end extending transversely of its elongated direction, and sides extending in its elongated direction between said base and said rim, said sides of said telescopic parts being disposed in spaced relationship so that there is no mutual guiding between said telescopic parts, said positive locking means being located in said base and said rim of said telescopic parts and when said telescopic parts are interconnected in the extended position, said base of the upper said telescopic part is located in the same plane with said rim of said lower telescopic part so that there is no overlapping of said telescopic parts in the extended position, said jib housing having a length at least equal to twice the length of each of said telescopic parts, and releasable catch means located at the upper end of said jib housing and arranged to hold at least one of said telescopic parts in a position within said housing spaced upwardly from the lower end of said housing.
 2. In a telescopic crane jib, as set forth in claim 1, wherein said telescopic parts include a lowermost telescopic part and at least one other said telescopic part arranged to extend outwardly from said lowermost part in the extended position, and in the retracted position the base of said lowermost telescopic part supports the bases of said other telescopic parts positioned above it.
 3. In a telescopic craNe jib, as set forth in claim 2, wherein a cylinder and piston assembly is positioned within said housing interiorly of said telescopic parts with said cylinder fixed to said base of the lowermost said telescopic part and said piston movably displaceable from said cylinder and secured to the lower end of said jib housing, said telescopic parts being slidably displaceable relative to and guided in the longitudinal direction by said cylinder and being secured relative to said cylinder against rotation.
 4. In a telescopic crane jib, as set forth in claim 3, wherein said telescopic part and said housing are each formed of a lattice frame construction extending for the full length of said telescopic parts between said base and said rim of each and for the full length of the lateral sides of said housing.
 5. In a telescopic crane jib, as set forth in claim 1, wherein said rim of each said telescopic part extends transversely outwardly from the upper end of said sides of said telescopic part and said base of each said telescopic part extends transversely inwardly from the lower end of said sides of said telescopic part, and in the extended position of said telescopic parts said upper rim of the lower one of two adjacent said telescopic parts has an inwardly facing surface juxtaposed to an outwardly facing surface on said base of the upper one of the two adjacent said telescopic parts, the inwardly facing surface of said rim and the outwardly facing surface of said base having corresponding tapers extending inwardly in the upward direction of said telescopic parts.
 6. In a telescopic crane jib, as set forth in claim 1, wherein two peak outriggers are positioned in the retracted position within said telescopic parts, means pivotally connecting said peak outriggers to said telescopic part located outermost in the fully extended position of said jib, and means for spreading said peak outriggers apart from each other when said outermost telescopic part is extended outwardly.
 7. In a telescopic crane jib, as set forth in claim 1, wherein said jib includes peak jib means connected to said telescopic part located outermost in the fully extended position.
 8. A crane jib as claimed in claim 1, wherein said releasable catch means includes a plurality of springloaded catches.
 9. In a telescopic crane jib, as set forth in claim 1, wherein said locking means on said telescopic parts are arranged to transmit compressive forces between the upper end of one said telescopic part and the lower end of the adjacent said telescopic part in the extended condition and also to transmit tensile forces therebetween.
 10. A crane jib as claimed in claim 9, wherein said locking means each comprises two bolts, a support, means locating said bolts for sliding movement in alignment with each other and in directions perpendicular to the longitudinal axis of said jib, said two bolts sliding in opposite directions in two adjacent telescopic parts whereby when one of said two bolts has been advanced, said two bolts are accurately aligned with each other by said support and advancement of the other of said two bolts causes said two bolts to engage with each other.
 11. A crane jib as claimed in claim 10, wherein said support includes means defining an opening corresponding to the cross section of the one of said two bolts on said adjacent telescopic part, said opening being in line, in the direction of the longitudinal axis of said jib with said one of said bolts, whereby when said one of said bolts has been advanced into a locking position and said adjacent telescopic part moves downwards relative to said support said one of said bolts rests on said support.
 12. A crane jib as claimed in claim 11, wherein said one of said bolts on said adjacent telescopic part which operates with said support has means defining an opening in which the upper of said bolts engages when said other bolt is advanced in the direction of said one bolt to form said second stage locking means.
 13. A cRane jib as claimed in claim 12, wherein said opening of said bolt of said adjacent telescopic part is a central bore and said other bolt includes a projection directed towards said one bolt, said projection engaging in said bore when the centres of said two bolts are equidistant from said support.
 14. A crane jib as claimed in claim 10, further comprising fluid pressure-operated cylinders and means operatively connecting one of said cylinders to each of said two bolts for advancing said bolts.
 15. A crane jib as claimed in claim 10, further comprising auxiliary safety devices operatively connected to each of said two bolts.
 16. A crane jib as claimed in claim 15, further comprising means for producing a warning signal, means connecting said means for producing a warning signal to said auxiliary safety devices and means for rendering said means for producing a warning signal inoperative when said auxiliary safety devices are operated to lock said two bolts in operative positions.
 17. A crane jib as claimed in claim 10, further comprising means for locking said telescopic parts to said jib housing when said telescopic parts are in said retracted positions.
 18. A crane jib as claimed in claim 17, wherein said means for locking said telescopic parts to said jib housing includes means for locking said telescopic parts at both their upper and lower ends to said housing.
 19. A crane jib as claimed in claim 18, comprising means defining openings in said telescopic parts and in said jib housing, said means including means defining wedge surfaces in said openings, and said bolts engaging said wedge surfaces when advanced into operative positions into said openings, said wedge surfaces compensating for manufacturing tolerances in distances between said locking means at the upper and lower ends of said telescopic parts.
 20. A crane jib as claimed in claim 19, further comprising means enabling said bolts to engage in said openings without clearance when said bolts are advanced into said openings with said telescopic parts in said retracted positions.
 21. A crane jib as claimed in claim 20, further comprising wedging devices cooperating with said bolts.
 22. A crane jib as claimed in claim 21, wherein said wedging devices include thrust pins, means mounting said thrust pins for movement perpendicular to the direction of movement of said bolts, fluid pressure-operated cylinder means and wedge means operatively connecting said fluid pressure-operated cylinder means to said thrust pins for urging said thrust pins one against each of said bolts.
 23. A crane jib as claimed in claim 21, wherein said wedging devices each include a further locking bolt, fluid pressure-operated cylinder means for actuating said further bolt and means defining wedge surfaces on said further bolt, said wedge surfaces engaging with one of said two bolts.
 24. A crane jib as claimed in claim 10, wherein said telescopic sections are each of rectangular cross section and wherein said bolts extend along diagonals of said rectangular cross section. 